Data driven pages: non-unique names allowed?

Discussion created by geejee on Dec 6, 2009
As opposed to the classic DS Mapbook the data-drivem pages in 9.4 do not require the pages names to be unique.
The ArcGIS Help says "Page names should be unique, though Data Driven Pages will accept null and duplicate values." That's confusing to me: Either the name has to be unique or not.

To avoid unwanted double pages I prefer the DS Mapbook approach. To have its usablity extended a warning like "Name XXX occurs YYY times" or even a message box with the complete list of non-unique values would be great.